The origins of science, and the scientific method, have to do with attempting to understand the world around us. Why things fall when we drop them. How to throw a rock so that it hits a target. Why some things float and others don’t. Why ice forms and why it melts. How to transform base metal into gold.
The original purpose of science was to make sense of the world. It was more than just curiosity. If we wanted to build a tall building, would it be possible to determine how tall we could make it before it fell over? If we wanted it to be a square shape, how would we lay it out? How much stuff can we pile into a boat before it becomes unstable and tips over? Even back in the stone age, there were people around who knew enough about these problems to be able to address them.
Originally, these were considered to be matters of philosophy. But as time passed, the study of such ‘practical’ philosophical concerns became a discipline unto itself, practiced by a very tiny cadre of serious experts. And study it they did…from all angles. Even the great Sir Isaac Newton devoted a considerable portion of his energies to the search for a way to transform base metal into gold. And though he was (naturally enough) unsuccessful in that particular endeavor, it didn’t deter him from actually publishing a recipe or two!
But as time passed, the steady accumulation of knowledge began to build impressively – so much so that as the 19th Century drew to a close a certain amount of hubris began to pervade some parts of the scientific community. Haughty claims were made that we now knew everything there was to know about physics, and going forward it would just be a case of putting that knowledge to useful and practical use. But the dawn of the 20th Century first introduced some disturbance to that arrogant posture, then kicked it in the nuts, and finally blew it out of the water.
The first disturbance was the discovery of the atom. Not that it happened overnight, but with Rutherford’s discovery of the electron a number of things were able to fall quickly into place. Previously it had been held that matter was more or less continuous. A small lump of iron was just a smaller version of a big lump of iron, identical in every way, and that was all there was to it. But now we were learning that all matter actually consisted of tiny building blocks called atoms, and that it was not possible to break an iron atom into smaller pieces and have those pieces still comprise iron.
Along with this discovery was the fact that atoms themselves were composed of further constituent parts – protons, neutron, and electrons. The trouble was that you couldn’t hold any of those exotic objects in your hand. You couldn’t even look at them under a microscope. All you had to go on were the results of a number of complicated experiments, which in total suggested only one possible set of interpretations.
This was a major turning point for science as a discipline because it was no longer describing the world we lived in, as we perceived it. We could never hope to observe an electron (for example) the way we can observe a bowling ball. Our interactions with electrons would be limited to experiments in which we were obliged to assume we were experimenting on electrons, and the things we would observe would then either confirm or deny some specific theory on the nature of electrons. This level of abstraction is commonplace in scientific thinking today, but left many people at the time disturbed by the apparent lack of direct meaning in terms of the real world. Today, the extreme indirection that characterizes the frontiers of theoretical physics can often be almost impossible for many non-expert observers to grasp.
Nonetheless, it soon became apparent that, provided we could place an abstract experiment in some practical real-world context, and interpret our experimental outcome in the light of some aspect of real-world relevance, we could learn to live with it. So, even though we cannot interact personally with atoms, everything we learned about them would continue to marry perfectly with everything we knew about the properties of materials made from these atoms. In fact, it would even enable us to explain many of the things we thought we already knew but couldn’t otherwise properly account for.
So that was the first shock to the system – that our universe is comprised of things we can’t actually see or touch. But that’s OK, because at least we understand the relationships between those constituent parts and the bits we can see and touch. And it all starts to makes profound sense, once you get comfortable with it.
Then the second shock to the system came along right behind it. Einstein’s theories of Special – and especially General – Relativity. These introduced concepts that simply couldn’t be reconciled with any normal view of the ‘real’ world as we experience it. Time passes at a different rate if you are in motion, or experiencing gravity. Likewise, you get heavier the faster you go. And, most perplexing of all, things which were observed by one observer to have happened simultaneously, can be inferred by a certain other observer to have happened one after the other.
This presents yet another level of difficulty to the skeptical observer, and particularly to the one expecting the world to conform to certain degree of homespun common sense. We are not being asked to interpret the results of an abstract experiment in the light of the universe we know and understand. Instead we are being asked to accept that we do not actually know and understand the universe after all. Fundamentals like the steady passage of time are no longer fundamental. General Relativity so thoroughly re-wrote the rules of the universe that even today there are still predictions arising from his theories that await experimental confirmation.
And, thus far at least, every last prediction of General Relativity, bar none, that have been testable, have been proven true. On a mundane level, in 1971 four atomic clocks were flown twice around the world in different directions on jetliners, and their time readings afterwards compared with stationary clocks on the ground. In each case real time differences were observed, and were found to be completely consistent with General Relativity. Today, GPS positioning systems have to take relativistic effects into account in order to achieve anything close to the accuracy required. And in the giant particle accelerators that were used to discover the famous Higgs Boson in 2013, protons are accelerated so close to the speed of light that Einstein predicts their mass should increase dramatically. Indeed, if this increase in mass were not very carefully taken into account, the accelerator wouldn’t actually work at all!
So the net result is that we have come to accept that the universe does not actually work in the simplistic way we have been used to over the last several thousand years. But so long as the guy who designs the GPS is au fait with it, we don’t need to be overly concerned.
The third blow, though, strikes right at the very heart of what we think we mean by the scientific method. That is, of course, quantum mechanics. And the conundrum at the core of quantum mechanics is its probabilistic nature. Science tells us what will happen – if A, then B. But Quantum Mechanics tells us “if A, then probably B”.
It used to be thought that if you could model the exact state of every particle in the universe at any particular moment, then you could determine exactly what would happen at every other moment in the future. But by the 1970’s, chaos theory had clarified that this is only true if you can stipulate all these things with infinite precision. Even so, if you believe that universe can presently be exactly described, with infinite precision, that would tend to imply that the entire future of the universe is therefore pre-determined. This is an idea that comforts some people, but troubles others. However, the inherently probabilistic nature of Quantum Mechanics tells us that the universe is not at all pre-determined. There is an element of fundamental uncertainty as to its exact state at any instant in time, and so pure chance has a significant role to play in how it evolves. In other words, even with the best, most advanced super-computers in the world at our disposal, there will still be some lingering uncertainty as to what tomorrow’s weather will be.
I’ll stop there with the specifics. But as with the mind-bending predictions of General Relativity, so the twilight zone of Quantum Mechanics continues to throw curveballs at us. Not only do those curveballs bend in both space and time, they can also be in two places at once, and you can never be absolutely certain whether it was even pitched at all! Furthermore, as with General Relativity, even the most bizarre machinations of Quantum Mechanics seem to prove out experimentally, one after the other.
Currently, the unknown frontiers of theoretical physics are connected primarily with one major issue related to General Relativity and Quantum Mechanics – the simple fact that we cannot reconcile the one with the other. You could simplify the problem and say that General Relativity is concerned with the universe on a large scale and has nothing to say on very small scales, whereas Quantum Mechanics is concerned with the universe on a small scale and has nothing to say on very large scales. What physicists would like to discover are relationships that fundamentally link the two. Things that, in effect, would allow a quantum mechanical description of General Relativity, or a relativistic description of Quantum Mechanics. Such things are referred to as Grand Unified Theories, or GUTs.
There are a few GUTs out there, of which the most promising is something you may have heard of – String Theory. It is a mathematically promising approach, but still has a long way to go, and might yet end up being a dead end. For the casual inquirer it has two mammoth drawbacks. The first is that, even if your grasp of General Relativity and Quantum Mechanics is strong enough that you feel a certain level of comfort with them, you have no chance whatever – absolutely zero – of making any sense of String Theory. It has been said that even the experts in the field can’t make any sense of it. The second is probably the reason for the first. Nothing in String Theory has any relationship whatsoever with the observable world. You cannot interpret any aspect of it in any physical way. It is, at its core, little more than a set of incomprehensibly complicated equations.
In other words, the theories at the very frontiers of the world of physics today don’t really make any ‘Sense’ whatsoever. At least not as we have become used to using that word.